Can anyone tell me what is the difference between and 737-277Adv and a 737-253Adv. I have seen others listed like 737-236Adv, 737-2M8Adv, 737-2H4Adv, 737-298Adv. What makes its a 277 or 253 etc? Also I've have seen a few 732 with no ADF antenna.

Also I have noticed that some of the few 737-200 still flying in US file as a B73Q/A. I know the Q means they can fly Rvsim and the /A is VOR DME only.

The last two digits or characters refer to the customer for whom the aircraft was built. Any Boeing you see in BA colors will have a series number ending in 36, as in 7x7-x36. If it's different, then you have a good indication the aircraft was built for another airline.

I'm sure there's someone on the forum who can provide a complete list.

There can be significant differences between two aircraft of the same series that are manufactured for different customers. Boeing was the first commercial builder to offer mass produced but customized aircraft. Perfect example of this is the 707-138 that Qantas used. Stock 707 wouldn't work financially so Boeing reduced capacity and increased range through redesign. Having gotten the drop on Douglas and other competitors, Boeing could afford to woo customers by optimizing their aircraft when Douglas and the others couldn't afford the additional engineering costs. This degree of variation within each aircraft model required the introduction of a customer code. Airbus doesn't need it because of their limited product range-bare bones every A319 is the same airplane mechanically. Not always so with Boeing.

"When a man runs on railroads over half of his lifetime he is fit for nothing else-and at times he don't know that."

Quoting Ptrjong (Reply 12):Don't the Boeing customer designations become pretty meaningless when an aircraft's interior configuration is changed during its service life?

Interiors are only a part of the customer options on Boeing aircraft. Differences in systems such as aux. fuel tanks, engine configs, instrumentation etc., to name a few are all part of the customer designation.

Quoting Ptrjong (Reply 12):Don't the Boeing customer designations become pretty meaningless when an aircraft's interior configuration is changed during its service life?

Well, they do help trace back the aircraft to its origins. Plus the configuration isn't that big of a deal, as for example some lessors like ILFC and GECAS order them with their own code at times, and not with the code of their respective customers. The configuration was a major thing during the times of the 707 and others, while today certain configurations like flightdeck custom mods for customers aren't really that well traceable.

Nowadays, the Boeing Customer Code only seems to show wfor whom the aircraft was built and maybe delivered, though exceptions do happen, like when AZ swapped the 747 for the 777, while some 747s were already in the assembly line (hence, when VS took delivery of AZ's brandnew 744s, they kept the AZ code), or when Continental didn't take delivery of their 763s.

Quoting Ptrjong (Reply 12):I'm sure you can have your Airbus the way you like it. Airbus just doesn't see the need for designations for such minor differences, I presume.

Don't the Boeing customer designations become pretty meaningless when an aircraft's interior configuration is changed during its service life?

I'll hazard a guess here: it all has to do with beancounters and logistics. Presumably the aircraft were indexed in some database at Boeing per customer. At Airbus, the system does not account for the customer in the same way.